Exhaust gas treatment device with a burner for generating a flame for the combustion of process gas

ABSTRACT

The invention relates to a burner as well as to a waste gas treatment device for generating a flame for the combustion of process gas, especially of contaminants, in a combustion chamber, in each case having feed lines for a fuel gas and for an oxidizing agent so that they flow into a pre-mixing chamber, and having an ignition device for igniting the gas mixture contained in the pre-mixing chamber. According to the invention, a sensor for detecting and/or monitoring the flame is provided on the burner, especially at one end of the burner situated opposite from the pre-mixing chamber.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application under 35 USC §§ 120 and 121 of U.S. patent application Ser. No. 16/912,836, filed Jun. 26, 2020, status pending, which claims priority to under 35 USC 11119 to German patent application 102019117331.0, filed Jun. 27, 2019, the contents of each of which is incorporated by reference.

FIELD OF THE INVENTION

The invention relates to a burner for generating a flame for the combustion of process gas and to a waste gas treatment device with a burner.

BACKGROUND OF THE INVENTION

Many industrial plants for processing semiconductor materials or for producing photovoltaic cells make use of gases for film deposition and for etching. Reactive and environmentally hazardous process gases and their reaction products generated during the process are often treated in local waste disposal facilities near the processing plant. Such toxic gases are also formed in large amounts, for example, during the production of semiconductor circuits and, due to their toxicity, they cannot be discharged into the environment without first being treated.

Aside from the process gases of such chemical vapor deposition (CVD) or dry-etching processes, waste gases stemming from other processes and containing contaminants can also be treated with the invention. Such toxic or environmentally hazardous gases are, for instance, SiH₄, SiH₂Cl₂, SiF₄, NH₃, PH₃, BCl₃, SF₆ or NF₃.

With the increasing demand for such modified substrates, there is thus also an ever-greater quantity of process gases that have to undergo treatment in order to ensure compliance with environmental and health safety requirements.

A common method for this consists of disposal by means of combustion and subsequent scrubbing with a scrubbing liquid. It is a known procedure to arrange a burner in the cover of a combustion reactor and to feed noxious gases through several pipes that open up in the vicinity of the flame.

The reaction products of the thermal treatment are present either in gaseous form or in solid form. After the water-soluble gases and the solid particles have been scrubbed out, the remaining gaseous reaction products such as water vapor or CO₂ can be released into the environment without any further after-treatment.

It goes without saying that a number of combustion methods and reaction chambers have already been developed and employed in actual practice for the thermal reaction. For instance, European patent specification EP 0 346 893 B1 discloses an arrangement for cleaning waste gases that consists of a reaction chamber in which a burner is arranged at the bottom that, on the one hand, is operated with fuel gases such as hydrogen and oxygen or air or else natural gas and air, and that, on the other hand, receives the waste gas that is to be cleaned. The reaction product generated during the combustion contains solid components as well as water-soluble reaction products.

Korean patent specification KR 1 275 475 B and Chinese Examined Application 102 644 928 B disclose a heat treatment device for waste gases containing harmful substances. These substances are converted into other compounds. The heat treatment device has a combustion chamber, one or more burners, one or more waste gas inlet openings and a waste gas outlet opening.

German patent application DE 10 342 692 A1 discloses a device with a combustion chamber that has at least one burner on a cover arranged at the top, so that a flame is directed from the top to the bottom into the interior of the combustion chamber. There is also a feed line for a scrubbing liquid with which a continuous film can be formed on the entire inner circumferential surface of the combustion chamber.

German patent application DE 10 2004 047440 A1 discloses a reactor chamber that has an outer and an inner wall, whereby the inner wall tapers downwards in the form of a funnel at a prescribed angle, and a device for the thermal treatment of the toxic gases that is arranged on the reactor chamber so as to seal it off towards the top. Inside the inner wall of the reactor chamber, there is a water film that flows uniformly downwards.

Japanese published unexamined patent application JP 2017 089985 A discloses a waste gas treatment device for the thermal treatment of a waste gas, having a combustion chamber for burning the waste gas. An ignition device has an air-fuel pre-mixing chamber and a spark plug for generating an ignition flame.

U.S. Pat. Appln. No. 2017/0065934 A1 and U.S. Pat. No. 9,956,525 B2 disclose an apparatus for purifying waste gases for an integrated semiconductor, having a cover with a burner mounted thereon to generate a flame and having a plurality of waste gas inlet pipes. A water curtain prevents the accumulation of by-products in the apparatus.

For safety reasons, combustion reactors are usually equipped with a flame detector. The flame detector serves to monitor the status of the burner so that, if the flame goes out, the feed of fuel gas and of noxious gases into the reactor is interrupted. Then, automatically switched three-way valves can convey the noxious gases past the reactor into another reactor or into a line for discharging hazardous waste air. A device of this generic type is disclosed in German patent document DE 10 2015 106 718.

Japanese published unexamined patent application JP 2017 089986 A discloses a combustion reactor with a liquid film on the wall, whereby a flame detector detects the flame right through the liquid film.

U.S. Pat. Appln. No. 2014/0106282 A1 discloses a device with two flame sensors that are directed from the side of a burner through an opening in the wall into the reaction chamber.

A drawback of the prior-art devices is the fact that ionization current monitoring is unstable and susceptible to errors. Particularly when oxygen is used as the oxidizing agent, the range of the ionization is narrowly limited and can shift if the quality of the gas varies, which would lead to an unreliable measurement of the ionization current. Moreover, it is necessary to avoid contact of the electrode with the combustion products of the noxious gas, in other words, with particles or acids, that lower the conductivity of the electrode.

This is why optical detection has already been suggested. For this purpose, the reaction chamber should be augmented with holes, although this is difficult to integrate into existing designs. Since, as rule, very little space is available on the cover of the reactor, additional drilled holes are often no longer possible there. Moreover, high temperatures in the area of the cover are detrimental for the detector and for the accuracy of the measured results. In view of the liquid flow along the inner wall, it is even more difficult to make a hole through the side wall of the reactor.

Before the backdrop of the disadvantages described above, the invention is based on an objective of thermally treating process gases containing contaminants, whereby a reliable and precise flame detection is to be achieved.

BRIEF SUMMARY OF THE INVENTION

The invention relates to a burner for generating a flame for the combustion of process gas, especially of contaminants, in a combustion chamber. There is a feed line for a fuel gas and a feed line for an oxidizing agent so that they flow into a pre-mixing chamber, and there is also an ignition device for igniting the gas mixture contained in the pre-mixing chamber.

According to the invention, a sensor for detecting and/or monitoring the flame is arranged on the burner, especially at one end of the burner situated opposite from the pre-mixing chamber.

The arrangement of the sensor or of the detector as a flame monitor in the burner translates into a very compact embodiment. Moreover, the sensor only comes into contact with clean burner gas, and the space in front of the sensor is constantly being flushed. In the prior-art arrangements, additional holes leading to the combustion chamber are necessary, and an additional flushing flow is always needed in order to protect the sensor. In the present invention, the sensor or detector can analyze the entire flame in every state. In contrast to the state of the art, there is no need for a pilot burner for ignition purposes since an ignition device is already integrated into the burner and an ignitable mixture is generated in the pre-mixing chamber.

Owing to the formation of particles during the combustion process, it is necessary to flush all of the connections on a waste gas treatment device that has the burner—a so-called reactor—in order to prevent the formation of deposits. For this reason, the number of holes made in the waste gas treatment device or in the reactor should be kept to a minimum.

The present invention, in contrast to the state of the art, requires neither an ignition burner nor a hole for a flame sensor. Moreover, the burner is particularly compact. As a result, the feed lines for noxious gas can be arranged very close to the flame.

According to a first advantageous embodiment of the invention, the fuel gas and the oxidizing agent can each be fed into the pre-mixing chamber of the burner in an essentially cylindrical pipe, whereby these cylindrical pipes are configured as outer and inner pipes that are concentric relative to each other, whereby the outer pipe and the inner pipe are arranged at a radial distance from each other. This makes it easy to assemble and disassemble the burner, in addition to which the production costs are lower and the structure becomes altogether more compact.

As set forth in the invention, aside from cylindrical pipes, pipes with other geometric shapes are likewise conceivable such as, for instance, polygonal, especially hexagonal, shapes.

Another advantageous variant of the invention provides for the sensor to be an optical sensor, especially an ultraviolet (UV) or infrared (IR) sensor, whereby the flame falls within the optical viewing field of the sensor. The sensor is easy to mount, and it is less malfunction-prone than electric measuring methods.

Thanks to the optical detection, flames with different types of fuel gas can be detected. In particular, the combustion of hydrogen can also be optically detected.

Different detectors with different optical spectral ranges are commercially available for various applications, so that there is an altogether broad range of applications.

Optical detection allows the burner to be operated with a feed of fuel gas through the outer pipe and a feed of oxygen through the inner pipe, or else with a feed of fuel gas through the inner pipe and a feed of oxygen through the outer pipe. It is likewise conceivable to employ an IR detector to detect the glowing of a fine wire in the flame inside the pre-mixing chamber. An IR detector is advantageous if the burner has been installed in the reactor in such a way that the viewing direction of the detector through the feed line is oriented towards a cold surface that is being flushed, for example, with liquid.

By the same token, it is also fundamentally conceivable to use an electric detection modality, that is to say, ionization current monitoring.

According to an advantageous embodiment of the invention, the viewing axis of the optical sensor coincides approximately with the longitudinal axis of the burner, in particular, the sensor detects and monitors the flame through the inner pipe of the burner. In this manner, a large detection field is covered, thus allowing a reliable and comprehensive detection as well as continuous monitoring of the flame. In the prior-art burners, the detector has only a restricted viewing field in the longitudinal direction of the flame.

In a refinement of the invention, a glass pane, especially a quartz glass pane, is arranged between the burner and the sensor, as a result of which the structure is likewise simplified and thus more cost-efficient. Moreover, the quartz glass pane separates the sensor from the fuel gas and also seals off the gas feed line. Consequently, the sensor has no contact with the fuel gas and does not have to be sealed itself.

It is particularly advantageous for the fuel gas to be carried in the outer pipe or in the inner pipe, and for the oxidizing agent to be carried in the outer pipe or in the inner pipe. Since there is no need for complete mixing in the pre-mixing chamber, the selection of the gas type that is on the outside can, to a certain extent, influence which chemical composition that makes contact with the noxious gas is predominant in the combustion chamber, for instance, a low-oxygen or high-oxygen chemical composition. This allows the efficiency of the combustion and the formation of nitrogen oxides to be influenced.

In a refinement of the invention, the inner and the outer pipes are electrically conductive and electrically insulated from each other by means of an insulator. A voltage for the ignition sparks can be applied between the pipes so that the gas mixture can be ignited.

According to an advantageous embodiment of the invention, the preferably optical sensor is electrically insulated vis-à-vis the inner pipe. When the ignition spark is generated by applying the high voltage, the sensitive optical sensor does not become electrically charged, as a result of which it is protected against destruction from excess voltage. This also prevents a falsification of the measured values that might be caused by the excess voltage.

Another advantageous embodiment of the invention provides for the ignition device to have at least one projection that is arranged on the lower end of the inner pipe and that is especially oriented towards the outside and/or for the ignition device to have at least one projection that is arranged on the outer pipe and that is especially oriented towards the inside in order to generate an ignition spark between the inner pipe and the outer pipe. The burner can be directly ignited by means of an ignition spark. In comparison to the state of the art, a relatively lower high voltage is needed for the ignition. The ignition functions reliably.

According to a refinement of the invention, the ignition device has an electrode that is arranged in the pre-mixing chamber and that serves to generate an ignition spark in the pre-mixing chamber. In this variant, the ignition voltage is not applied via a pipe that carries gas but rather via an electrode that is inserted in such a way as to be insulated and that opens up in the pre-mixing chamber, and the ignition spark is generated against the grounded outer pipe. In this context, it is advantageous that all of the burner parts can be grounded and only one insulated feed line has to be implemented in the mixing chamber.

In another variant of the invention, the outer pipe is electrically grounded and the inner pipe is connected to an ignition adapter or ignition transformer via a connector for high voltage in order to generate an ignition spark from the inner pipe to the outer pipe. One of the pipes is grounded while the other one, preferably the inner pipe, is connected to a voltage source. In this manner, an ignition spark can be systematically generated at the end of the inner pipe in the transition area to the mixing chamber. The electric insulation can be achieved more easily if it is located in the cold part of the burner. For electric safety reasons, the outer pipe should be grounded and the inner pipe should carry the ignition voltage. Otherwise, the risk of the ignition voltage being discharged to the outside would be greater.

It can be provided for the inner pipe to be configured as an electrode for measuring the ionization current in the pre-mixing chamber. When the inner pipe is installed so as to be electrically insulated, it is not only possible for the ignition voltage to be carried through it, but also for a flame signal to be generated in the form of a rectified current component by means of an applied alternating voltage—as long as there has been no ignition. Moreover, the electric detection can be employed as a redundant signal with an eye towards increasing the safety of the burner.

According to another advantageous embodiment of the invention, the outer pipe is made of electrically insulating ceramic, at least in the area of the pre-mixing chamber. The pre-mixing chamber can be formed by the lower end of the outer pipe. It is likewise conceivable for the entire pipe to be made of insulating ceramic.

In a refinement of the invention, a temperature-resistant wire, the so-called glow wire, is arranged in the pre-mixing chamber and it projects into the optical viewing field of the sensor. In the pre-mixing chamber, a flame is already being formed in the areas where the fuel gas and the oxidant mix, and this causes the wire to heat up. The wire continues to be heated up by the flame that is forming until the wire starts to glow, which is then visible, for example, by means of an IR detector. If the wire is very thin, it cools off rapidly once the flame has been extinguished, so that it can be utilized as a way to detect the flame. This prevents a so-called afterglow, which would yield an undesired false positive signal.

According to another advantageous embodiment of the invention, it is provided for a flame holder to be arranged in the pre-mixing chamber in order to generate turbulence. The flame holder is needed when air is used as the oxidizing agent instead of oxygen since then, the flame speed is so low that the flame would be blown out of the pre-mixing chamber if there were no flame holder. The turbulence generated at the flame holder stabilizes the flame at the flame holder. The flame holder can be electrically connected to the outer pipe and can be employed to generate the ignition spark.

For mechanical stabilization or centering purposes, at least one spacer can be provided between the inner pipe and the outer pipe. As a rule, the spacers are configured so as to be electrically insulating, since otherwise the generation of a spark would not work.

According to a refinement of the invention, a tubular connecting piece is provided between the outer pipe and the sensor, and it has the feed line that carries the fuel gas or the oxidizing agent to the inner pipe. In this manner, the burner can be easily assembled and disassembled, and its size and length can be varied by using different connecting pieces. Moreover, the connecting piece serves to establish the electrically insulated connection of the gas feed line and of the sensor. It can be electrically grounded itself.

In another embodiment of the invention, it is provided for the glass pane with the sensor to be arranged at one end of the essentially cylindrical connecting piece, and for the inner and/or outer pipe that is electrically insulated by an insulator to be arranged at the other end. This renders the structure of the burner simpler and more compact.

The structure of the burner can be further improved if the connector for the ignition device, especially for the high voltage, is provided between the connecting piece and the outer pipe.

According to an independent idea of the invention, a waste gas treatment device or a so-called reactor is provided which has at least one burner arranged in a combustion chamber for generating a flame for the combustion of process gas, preferably noxious gases.

The device has at least one feed means for the process gas and at least one discharge means for the thermally treated waste gases.

The integration of the flame detector into the burner gives the waste gas treatment device a compact shape, and the feed means for the process gas can be brought very close to the flame in the reactor. This allows a more intense interaction of the flame with the process gas.

Owing to the formation of particles during the combustion process, all of the connectors on the waste gas treatment device or on the reactor have to be flushed in order to prevent deposits. For this reason, the number of holes in the reactor should be kept to a minimum.

The present invention requires neither an ignition burner nor a hole for a flame sensor. Moreover, the burner is very compact, as a result of which the feed lines for the noxious gas can be placed very close to the flame.

In particular, it is also possible for the burner and the noxious gas feed means to be integrated into a module. Here, for instance, the burner can be positioned in the center, and the noxious gas inlets can be positioned around the burner in a compact module. This translates into a reduction in the number of screwed connections needed on the cover of the reactor, and the noxious gas feed means can be brought very close to the burner or to the flame.

According to a first advantageous refinement of the waste gas treatment device according to the invention, when the burner in its assembled position, it is situated above the combustion chamber, especially approximately perpendicular to the waste gas treatment device. This ensures a uniform interaction of the flame with the noxious gases in the combustion chamber.

The design comprising a vertically installed burner simplifies the use of optical detectors that have moving parts such as, for example, closure flaps or so-called shutters for self-monitoring.

According to an advantageous embodiment of the invention, a feed line is provided for a flushing gas, especially nitrogen, whereby the flushing gas can flow in over porous sintered elements at the ends of the feed means for the process gas in order to displace particles. In some processes, especially the noxious gas outlet leading into the reactor, deposits build up due to returning moisture, oxidant or even due to thermal reactions. However, it can also be advantageous to feed in heated flushing gas, particularly in the case of process gases that tend towards condensation on cold surfaces.

According to another advantageous embodiment of the invention, liquid feed lines are provided, especially on the side wall of the combustion chamber. The burner according to the invention can be deployed in a waste gas treatment device or in a reactor over whose wall liquid flows. In order to protect the noxious gas inlets from splashing liquid, a small collar can be installed on the side wall in front of the liquid feed lines. For better thermal insulation, the cover of the reactor can be configured with a double wall. An elevated surface temperature on the inside of the cover reduces the probability that deposits of solids will build up. A flushing gas such as, for instance, nitrogen can be fed in through the double-walled cover, and this gas flows in over porous sintered elements at the ends of the noxious gas feed lines in order to displace particles.

According to a refinement of the method, a plunger is provided for cleaning deposits on the feed means for the process gas. If deposits nevertheless build up on the walls in a noxious gas inlet, they can be automatically scraped off by the plunger. As another alternative, a nozzle can be installed in the noxious gas inlet and, at certain points in time or if the pressure rises in the noxious gas line, it generates a gas pulse to blast away deposits on the wall. Cleaning with a liquid jet from a nozzle installed in the noxious gas inlet is also possible. In order to prevent deposits on the reactor cover, a flushing gas can flow in from the edge of the cover to the middle of the cover.

Due to the compact design of the burner, it is also possible to have embodiments with several burners on one waste gas treatment device or on one reactor. For this purpose, for example, the noxious gas feed means are arranged in the middle of the reactor cover, and two or more burners are arranged along an outer circle around these feed means, preferably with a slight slant of the flame towards the middle. The burners can also be slanted in such a way that they create an eddy in the reactor, thus allowing a more stable flow and better mixing in the reactor.

In the burner according to the invention, the ignition and the flame detection are integrated, so that other designs are conceivable in which one or more burners extend into the combustion chamber through the side wall over which liquid flows, said burners acting upon the noxious gas stream that is fed in from above through the cover.

With an eye towards attaining a particularly slender configuration of the waste gas treatment device, the burner can be arranged in the middle of the cover of the reactor and the noxious gas feed means can pass through the side wall of the reactor.

According to another advantageous embodiment of the invention, at least one feed line is provided for a reaction gas, especially an oxidizing agent and/or a reducing agent. Even though the burner allows the fuel gas-oxidant ratio to be varied, for certain processes, it might be necessary to feed additional oxidant, for instance, air or oxygen or a reducing agent such as fuel gas, into the reactor. Such feed lines for reaction gases can be installed in the cover of the reactor.

According to another advantageous embodiment of the invention, the waste gas treatment device has at least two burners arranged on the combustion chamber, whereby each burner is associated with a separate feed means for the fuel gas or for the oxidizing agent. This embodiment provides redundancy during the operation of the burner, thus avoiding high downtime costs for the process plants if a burner fails and when a burner has to be maintained.

A refinement of the invention provides for a regulation and/or control unit to regulate and/or control the feed means for the fuel gas or for the oxidizing agent, especially as a function of a signal from the sensor that is arranged on the appertaining burner and that serves to detect and/or monitor the flame of the appertaining burner.

It can be provided that the sensor is a flame ionization electrode. In this embodiment of the waste gas treatment device, the electrode can be inserted into the flame through the burner, especially through the inner pipe, in order to prevent the electrode from becoming soiled. When it comes to the flame monitoring of several burners, electric flame monitoring can be more advantageous than optical flame monitoring since it systematically monitors the flame of the associated burner. Optical flame monitoring systems occasionally detect the flame of several burners so that the status of an individual burner either cannot be ascertained at all or else not exactly.

Additional objectives, advantages, features and application possibilities of the present invention ensue from the description below of an embodiment making reference to the drawing. In this context, all of the described and/or depicted features, either on their own or in any meaningful combination, constitute the subject matter of the present invention, also irrespective of their compilation in the claims or the claims to which they refer back.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing summary, as well as the following detailed description of the disclosure, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the disclosure, there is shown in the drawings embodiments which are presently preferred. It should be understood, however, that the disclosure is not limited to the precise arrangements and instrumentalities shown.

In this context, the following is shown, at times schematically:

FIG. 1 a burner with an ignition device and with a sensor,

FIG. 2 to FIG. 10 the burner as shown in FIG. 1 in various embodiments,

FIG. 11 a module for a waste gas treatment device with a burner as shown in FIG. 1 to FIG. 10 ,

FIG. 12 a module for the waste gas treatment device with a plunger, a sintered element and a feed line for flushing gas,

FIG. 13 a module for the waste gas treatment device with a feed line for a cleaning medium, having a nozzle,

FIG. 14 the waste gas treatment device with a quenching area as well as a discharge means for thermally treated waste gases,

FIG. 15 and FIG. 16 additional embodiments of the waste gas treatment device,

FIG. 17 a waste gas treatment device with a subsequent scrubbing station and a liquid circulation system,

FIG. 18 another embodiment of the waste gas treatment device with two burners and separate feed means,

FIG. 19 another depiction of the waste gas treatment device as shown in FIG. 18 , and

FIG. 20 a burner with flame monitoring configured in the form of an ionization electrode.

DESCRIPTION OF THE DISCLOSURE

For the sake of clarity, identical components or those having the same effect are provided with the same reference numerals in the following figures, making reference to an embodiment.

FIG. 1 shows a burner 1 for generating a flame 33 for the combustion of process gas, especially contaminants, in a combustion chamber.

The feed lines 5, 6 serve to allow a fuel gas and an oxidizing agent to flow into a pre-mixing chamber 12.

An ignition device 10, 11 is provided for igniting the gas mixture present in the pre-mixing chamber 12.

FIG. 1 likewise shows a sensor 4 for detecting and/or monitoring the flame 33 that is arranged on the burner 1, especially at one end of the burner 1 situated opposite from the pre-mixing chamber 12.

As shown in FIG. 1 as well as in FIGS. 2 to 10 , the fuel gas and the oxidizing agent are each fed into the pre-mixing chamber 12 of the burner 1 in an essentially cylindrical pipe 2, 3. The cylindrical pipes 2, 3 are configured as an outer pipe 2 and an inner pipe 3 that are concentric relative to each other, whereby the outer pipe 2 and the inner pipe 3 are arranged at a radial distance from each other. Depending on the application purpose, the fuel gas can be conveyed in the outer pipe 2 or in the inner pipe 3 and the oxidizing agent can be correspondingly conveyed in the outer pipe 2 or in the inner pipe 3.

In the present embodiment, the inner pipe 3 and the outer pipe 2 are electrically conductive and electrically insulated from each other by means of an insulator 7.

In the embodiment as shown in FIGS. 8, 9 and 10 as well as in FIGS. 1 to 6 , the outer pipe 2 is electrically grounded and the inner pipe 3 is connected to an ignition adapter or ignition transformer via a connector 11 for high voltage in order to generate an ignition spark from the inner pipe 3 to the outer pipe 2. In this manner, an ignition spark can be systematically generated at the end of the inner pipe 3 in the transition area to the mixing chamber 12. For electric safety reasons, the outer pipe 2 should be grounded and the inner pipe 3 should carry the ignition voltage.

It can be provided for the inner pipe 3 to be configured as an electrode for measuring an ionization current in the pre-mixing chamber 12. When the inner pipe 3 is installed so as to be electrically insulated, it is not only possible for the ignition voltage to be carried through it but also for a flame signal to be generated in the form of a rectified current component by means of an applied alternating voltage—as long as there has been no ignition. Moreover, the electric detection can be employed as a redundant signal with an eye towards increasing the safety of the burner 1. As shown in FIGS. 1 to 10 , for purposes of mechanically stabilizing or centering the pipes 2, 3, at least one spacer 9 can be provided between the inner pipe 3 and the outer pipe 2. These spacers 9 are configured so as to be electrically insulating, since otherwise it would not be possible to generate a spark between the pipes 2, 3.

The embodiments as shown in FIGS. 1 to 10 illustrate that a tubular connecting piece 34 is provided between the outer pipe 2 and the sensor 4, and it has the feed line 5 to the inner pipe 3 for the fuel gas or for the oxidizing agent. A glass pane 8, especially a quartz glass pane, and the sensor 4 are arranged at one end of the essentially cylindrical connecting piece 34, while the inner pipe 3 and/or the outer pipe 2, which are electrically insulated by an insulator 7, are arranged at the other end. The connecting piece 34 serves primarily to establish the electrically insulated connection of the gas feed line and of the sensor. It can be electrically grounded.

In the present embodiment, the sensor 4 is configured as an optical sensor, especially a UV or IR sensor, whereby the flame 33 falls within the viewing field of the sensor 4. The optical sensor 4 is electrically insulated vis-à-vis the inner pipe 3.

As can also be seen in FIGS. 1 to 10 , the viewing axis of the sensor 4 coincides approximately with the longitudinal axis of the burner 1, so that the sensor element is aimed through the inner pipe 3. Therefore, the sensor 4 detects and monitors the flame 33 right through the inner pipe 3 of the burner 1.

The embodiment as shown in FIG. 10 illustrates that a temperature-resistant wire 14, especially a glow wire, is arranged in the pre-mixing chamber 12 and it projects into the optical viewing field of the sensor 4.

As shown in FIGS. 1 to 6 and 8 to 10 , the connector 11, particularly for the high voltage that is to be applied, is provided between the connecting piece 34 and the outer pipe 2.

The ignition device 10, 11 has at least one projection 10 that is arranged on the lower end of the inner pipe 3 and that is especially oriented towards the outside.

As shown in FIG. 5 , FIG. 6 and FIG. 9 , it can also be provided for the ignition device 11 to have at least one projection 35 that is arranged on the outer pipe 2 and that is especially oriented towards the inside, in order to generate an ignition spark between the inner pipe 3 and the outer pipe 2.

This projection 35 can be configured so as to be, for example, prong-like or pointed, as shown in FIG. 5 , or else rod-like, as shown in FIG. 6 . As set forth in the invention, other geometric shapes are, of course, also conceivable. FIG. 9 shows, for example, projections 35 that are oriented upwards.

As shown in FIG. 7 , the ignition device 10, 11 has an electrode 36 that is arranged in the pre-mixing chamber 12 and that serves to generate an ignition spark in the pre-mixing chamber 12. In this embodiment, the ignition voltage is not applied via a pipe 2, 3 that carries gas, but rather via the electrode 36 that is inserted in such a way as to be insulated and that opens up in the pre-mixing chamber 12, and the ignition spark is generated against the grounded inner pipe 3.

It can be provided for the outer pipe 2 to be made of electrically insulating ceramic, at least in the area of the pre-mixing chamber 12.

The embodiment as shown in FIG. 8 and FIG. 9 illustrates that a flame holder 13 can be provided in the pre-mixing chamber 12 in order to generate turbulence.

In the embodiment as shown in FIG. 1 , the projection 10 is formed on the inner pipe 3 as a central projection, in contrast to which FIG. 2 shows an embodiment in which the projection 10 is formed by points or tines that are oriented towards the outside. As shown in FIG. 3 , these points can run at a slant. The configuration of the projections allows the flow of gases into the pre-mixing chamber 12 and thus also allows the shape of the flame 33 to be influenced.

FIGS. 11 to 17 show a waste gas treatment device 22, or a so-called reactor, which has at least one burner 1 arranged in a combustion chamber 32 for generating a flame 33 for the combustion of process gas, preferably noxious gases. In particular, this can be a burner 1 as described above.

The waste gas treatment device 22 has at least one feed means 16 for the process gas and at least one discharge means 31 for the thermally treated gases.

In this context, the burner 1 and the noxious gas feed means 16 are integrated into a module 15. Here, for instance, the burner 1 can be positioned in the center, and the feed means 16 for the process gas can be positioned around the burner 1 in this compact module 15. This translates into a reduction in the number of screwed connections needed on the cover of the waste gas treatment device 22, and the feed means 16 for the process gas can be brought very close to the burner 1 or to the flame 33.

The design entailing a vertically installed burner simplifies the use of optical detectors that have moving parts such as, for example, closure flaps or so-called shutters for self-monitoring.

Particularly FIGS. 11 to 13 illustrate a module 15 as a part of the waste gas treatment device 22 shown in detail in FIG. 17 .

As shown in FIGS. 11 to 13 as well as in FIGS. 16 and 17 , when the burner 1 in its assembled position, it is situated above the combustion chamber 32, especially approximately perpendicular to the waste gas treatment device 22.

In the present embodiment as shown in FIG. 12 , at least one feed line 19 is provided for a flushing gas, especially for nitrogen. The flushing gas can flow in over porous sintered elements 18 at the ends of the feed means 16 for the process gas in order to displace particles. Especially at the outlet leading into the waste gas treatment device, deposits build up due to returning moisture, oxidant or even due to heat, and these can be flushed away with the flushing gas.

The typical applications make use of gases that, when heated or reacted with oxygen or moisture, form solids that can be deposited on all surfaces. Mechanical cleaning implements such as, for instance, scrapers, can be employed to remove such deposits from the interior surfaces of the reactor. These implements, however, are susceptible to malfunction. For this reason, the burner 1 according to the invention is preferably used in a reactor or in a waste gas treatment device 22 having a wall over which liquid flows.

As shown in FIGS. 14 to 17 , liquid feed means 23 are provided, especially on the side wall of the combustion chamber 32, for the waste gas treatment device 22 or for the reactor over whose wall a liquid flows. In order to protect the feed means 16 for the process gas or the noxious gas inlets from splashing liquid, a small collar 24 can be installed on the side wall in front of the liquid feed lines 23, as can be seen in FIGS. 14 to 16 .

For better thermal insulation, the cover of the waste gas treatment device 22 can be configured with a double wall. An elevated surface temperature on the inside of the cover reduces the probability that deposits of solids will build up. A flushing gas such as, for instance, nitrogen can be fed in through the double-walled cover, and this gas flows over porous sintered elements at the ends of the noxious gas feed lines in order to displace particles.

According to the embodiment shown in FIG. 13 , it is provided for a nozzle 20 to be installed in the noxious gas inlet 16 and, at certain points in time or if the pressure rises in the noxious gas line 16, it generates a gas pulse to blast away deposits on the wall. Cleaning with a liquid jet from a nozzle 20 installed in the noxious gas inlet 16 on a feed means 21 for cleaning media is also possible. In order to prevent deposits on the cover of the waste gas treatment device 22, a flushing gas can flow in from the edge of the cover all the way to the middle of the cover.

Even though the burner 1 allows a variation of the fuel gas-oxidant ratio, for certain processes it might be necessary to feed additional oxidant, for instance, air or oxygen or a reducing agent such as fuel gas, into the combustion chamber 32. Such feed lines 25 for reaction gases can be installed in the cover of the reactor 22.

As shown in FIG. 15 , there is at least one feed line 25 for a reaction gas, especially for an oxidizing agent and/or a reducing agent.

It can be seen in FIG. 14 that the discharge means 31 for the thermally treated waste gases of the waste gas treatment device 22 opens up into a quenching area 30 for purposes of quickly cooling off the gas after the combustion.

FIG. 17 shows a scrubbing station that has a wet scrubber 26, a heat exchanger 28 and a pump 29 and that is downstream from the waste gas treatment device 22. In this washing station, soluble gases and also particles such as, for instance, solids and acids formed during the combustion, are scrubbed out with a scrubbing liquid. The scrubbing liquid is conveyed by means of the pump 29 into the scrubbing segment and into the waste gas treatment device via the heat exchanger 28 and via means—not shown here—for regulating and measuring the throughput flow, and the scrubbing liquid then flows back into a storage tank. The storage tank has feed lines for fresh water and for alkaline solution for regulating the pH value and a drain for emptying purposes as well as sensors for the filling level, for the pH value and for the temperature. The scrubbing station can be connected to exhaust unit so a negative pressure can be generated in the waste gas treatment device 22.

Thanks to the compact design of the burner, configurations with several burners 1 on a waste gas treatment device 22 or on a reactor are also possible. For this purpose, for instance, the noxious gas feed means 16 are arranged in the middle of the reactor cover, and two or more burners 1 are arranged along an outer circle around these feed means, preferably with a slight slant of the flame 33 towards the middle. The burners 1 can also be slanted in such a way that they create an eddy in the reactor 22, thus allowing a more stable flow and better mixing in the reactor 22. FIGS. 14 and 15 show embodiments with two burners 1. Several, especially two, burners 1 are also provided in the embodiments shown in FIGS. 18 to 20 .

Since the ignition and flame detection are integrated into the burner according to the invention, other designs are conceivable in which, as shown in FIG. 15 , one or more burners 1 extend into the reactor 22 through the side wall over which a liquid flows, said burners 1 acting from the side upon the noxious gas stream that is fed in from above through the cover.

If the reactor is to be designed with a particularly slender configuration, it is also possible to implement a design in which the burner 1 is arranged in the middle of the cover of the reactor, and the noxious gas feed means passes through the side wall of the reactor 22, as can be seen in FIG. 16 .

Another embodiment of the waste gas treatment device can be seen in FIGS. 18 to 20 . This shows a method for waste gas disposal involving a combustion reactor or a waste gas treatment device 22 on which there are at least two burners 1. In this manner, if one of the burners 1 fails, the reactor 22 can continue to operate with at least one additional burner 1.

As can be seen in FIG. 18 and FIG. 19 , the two burners 1 have feed means 37, 38 for the fuel gas or the oxidizing agent that are independent from each other, so that the fuel gas or the oxidizing agent for each burner 1 can be regulated independently of each other by means of a regulation and/or control unit 39. Moreover, the burners 1 can also be ignited independently of each other by means of separate ignition devices. Each burner 1 has its own pre-mixing chamber 12.

Furthermore, each burner 1 in the embodiments shown in FIGS. 18 to 20 has flame monitoring that is separate and independent from the other burners 1, whereby the flame monitoring is preferably integrated into the burner 1 in such a way that it detects only the flame of the one burner but not the flame of the other burner 1 or of the combustion reaction in the combustion reactor 22.

In the present embodiment as shown in FIG. 20 , the flame monitoring is configured as an ionization electrode 40 so that the appertaining sensor detects the flame formation in the pre-mixing chamber 12 of the associated burner 1. The electrode 40 can be inserted through the burner 1, preferably through the inner pipe 3, into the flame 33. When it comes to the flame monitoring of several burners 1, electric flame monitoring can be more advantageous than optical flame monitoring since it systematically monitors the flame 33 of the associated burner 1.

It is also conceivable to have an embodiment variant with a burner as shown in FIG. 10 , whereby the glow wire 14 is arranged in the pre-mixing chamber 12, and an optical sensor, especially an IR sensor, is arranged on the opposite end of the burner 1. For this variant, it is advantageous for the reactor or the waste gas treatment device 22 to have a surface over which water flows, at least in the viewing direction of the sensor 4, so that no glowing surface in the reactor 22 can interfere with the flame detection.

If the flame 33 from a burner 1 is extinguished, thanks to the independent flame monitoring, only the supply of fuel gas or oxidizing agent—that is to say, the feed means 37, 38—for this particular burner 1 is blocked, which is done by means of the regulation and/or control unit 39. The other burners 1 are not affected by this.

The oxidant here can be oxygen, oxygen-rich air, or air.

As can likewise be seen in FIG. 18 , the noxious gas feed means 16 are equipped with a bypass valve 27. The feed means 37, 38 for the fuel gas or for the oxidizing agent has a flushing gas connector 41 downstream from the last shut-off valve of the regulation or control unit 39 for the fuel gas or for the oxidizing agent.

The method for waste gas disposal as shown in FIGS. 18 to 20 will be described in greater detail below. A failure of a burner 1 is detected by means of the sensor 4 of the flame monitoring, and the feed of fuel gas and oxidizing agent is interrupted by the regulation or control unit 39. After the failure of the burner 1, a comparison of the sensor signals serves to check whether the second or additional burners 1 is/are still active.

In the eventuality that other burners 1 are still active, the burner 1 that has failed is re-ignited by means of its own ignition device, without any interruption in the waste gas disposal. The bypass valve 27 upstream from the reactor 22 remains connected in the direction of the reactor 22. If both or all of the burners 1 have failed, the bypass valve 27 is deployed to feed the noxious gas into a bypass 42 and a signal is provided with which the upstream process can be switched off.

In the case of a failure of a burner 1, the fuel gas stream to the other burner 1 can be temporarily increased. When a burner 1 fails or is switched off, a flushing stream can be fed via the flushing gas connector 41 through this burner 1 in order to keep the burner 1 free of moisture, particles and corrosive substances.

This embodiment shown in FIGS. 18 and 19 provides redundancy during the operation of the burner 1, thus avoiding high downtime costs for the process plants when a burner malfunctions. The burners 1 can be arranged at any desired distance from each other and in any desired orientation since they are not required for through-ignition.

LIST OF REFERENCE NUMERALS

-   -   1 burner     -   2 outer pipe     -   3 inner pipe     -   4 sensor     -   5 feed line to the inner pipe     -   6 feed line to the outer pipe     -   7 insulator     -   8 glass pane/quartz glass pane     -   9 spacer     -   10 projection     -   11 connector for high voltage     -   12 pre-mixing chamber     -   13 flame holder     -   14 glow wire     -   15 module     -   16 feed means for process gas     -   18 sintered element     -   19 feed line for flushing gas     -   20 nozzle     -   21 feed means for cleaning medium     -   22 waste gas treatment device     -   23 liquid feed means     -   24 collar     -   25 feed line for reaction gases     -   26 wet scrubbers     -   27 bypass valve     -   28 heat exchanger     -   29 pump     -   30 quenching area     -   31 discharge means for thermally treated waste gases     -   32 combustion chamber     -   33 flame     -   34 tubular connecting piece     -   35 projection of the outer pipe     -   36 electrode     -   37 feed means     -   38 feed means     -   39 regulation and/or control unit     -   40 ionization electrode     -   41 flushing gas connector     -   42 bypass 

1. A waste gas treatment device (22), comprising: a combustion chamber (32) that has at least one feed (16) through which a process gas to be thermally treated is introduced into the combustion chamber (32) and at least one discharge (31) from which thermally treated waste gases are discharged out of the combustion chamber (32); and at least one burner (1) for generating a flame (33) for the combustion of process gas in the combustion chamber (32) comprising: feed lines (5, 6) for a fuel gas and for an oxidizing agent configured so that the fuel gas and oxidizing agent flow into a pre-mixing chamber (12) to form a gas mixture, wherein each of the fuel gas and the oxidizing agent are fed into the pre-mixing chamber (12) of the burner (1) in a substantially cylindrical pipe (2, 3) configured as outer (2) and inner (3) pipes of different lengths that are concentric relative to each other with the outer pipe (2) extending axially beyond the length of the inner pipe (3), and with the fuel gas being carried in one of the outer pipe (2) or in the inner pipe (3), and the oxidizing agent being carried in the other of the outer pipe (2) or in the inner pipe (3), wherein the inner pipe (3) and the outer pipe (2) each are electrically conductive, and wherein the premixing chamber (12) is within the outer pipe (2) at or near an outlet end of the outer pipe (2), and wherein the inner pipe (3) has a lower end, an insulator (7) configured to electrically insulate the inner pipe (3) from the outer pipe (2), an ignition device (10, 11) for igniting the gas mixture contained in the pre-mixing chamber (12), wherein the ignition device (10, 11) has at least one projection (10) arranged on the lower end of the inner pipe (3) and oriented towards an outlet of the burner (1) in order to generate an ignition spark from the inner pipe (3) to the outer pipe (2) in the pre-mixing chamber (12), and a sensor (4) for detecting and/or monitoring the flame (33) arranged at one end of the burner (1) situated opposite from the pre-mixing chamber (12).
 2. The waste gas treatment device (22) according to claim 1, wherein the burner (1) as assembled is situated above the combustion chamber (32), and approximately perpendicular to the waste gas treatment device (22).
 3. The waste gas treatment device (22) according to claim 1 wherein a feed line for a flushing gas, especially nitrogen, is configured so that the flushing gas flows over porous sintered elements (18) at the ends of the feed means (16) for the process gas in order to displace particles.
 4. The waste gas treatment device (22) according to claim 1, further comprising liquid feed lines (23) on the side wall of the combustion chamber (32).
 5. The waste gas treatment device (22) according to claim 1, wherein at least one feed line (25) is provided for a reaction gas that may comprise an oxidizing agent and/or a reducing agent.
 6. The waste gas treatment device (22) according to claim 1, wherein at least two burners (1) are arranged on the combustion chamber (32), and each burner (1) is associated with a separate feed (37, 38) for the fuel gas or for the oxidizing agent, respectively.
 7. The waste gas treatment device (22) according to claim 1, further comprising: a regulation and/or control unit (39) to regulate and/or control the feed (37, 38) for the fuel gas or for the oxidizing agent, especially as a function of a signal from the sensor (4) that is arranged on one of the burners (1) and that serves to detect and/or monitor the flame (33) of the respective one of the burners (1).
 8. The waste gas treatment device (22) according to claim 6 wherein the at least one sensor (4) is an ionization electrode (40).
 9. The waste gas treatment device (22) according to claim 1, wherein the sensor (4) is an optical sensor with an optical viewing field, and wherein the flame (33) falls within the optical viewing field of the sensor (4).
 10. The waste gas treatment device (22) according to claim 9, wherein the burner (1) has a longitudinal axis and wherein the optical sensor (4) has a viewing axis that coincides approximately with the longitudinal axis of the burner (1) so that the sensor (4) detects and monitors the flame (33) through the inner pipe (3) of the burner (1).
 11. The waste gas treatment device (22) according to claim 9, wherein a glass pane (8) is arranged between the burner (1) and the sensor (4).
 12. The waste gas treatment device (22) according to claim 1, further comprising: a tubular connecting piece (34) between the outer pipe (2) and the sensor (4) which tubular connecting piece (34) holds the feed line (5) to the inner pipe (3) for the fuel gas or for the oxidizing agent.
 13. The waste gas treatment device (22) according to claim 12, wherein a glass pane (8) is arranged at one end of the substantially cylindrical connecting piece (34), and the inner pipe (3) and/or the outer pipe (2) that is electrically insulated by an insulator (7) is arranged at the other end.
 14. The waste gas treatment device (22) according to claim 12, wherein the connector for the ignition device (11) is provided between the connecting piece (34) and the outer pipe (2) of the burner (1).
 15. The waste gas treatment device (22) according to claim 1, wherein the burner (1) further comprises a flame holder (13) in the pre-mixing chamber (12) configured to generate turbulence.
 16. The waste gas treatment device (22) according to claim 1, further comprising: a temperature-resistant wire (14) arranged in the pre-mixing chamber (12) of the burner (1) and projecting into the optical viewing field of the sensor (4).
 17. The waste gas treatment device (22) according to claim 1, wherein the ignition device (10, 11) further comprises at least one projection (35) that is arranged on the outer pipe (2) and that is oriented towards the inside in order to generate an ignition spark between the inner pipe (3) and the outer pipe (2).
 18. The waste gas treatment device (22) according to claim 1, wherein the ignition device (10, 11) as an alternative to the projection (10) has an electrode (36) in the pre-mixing chamber (12) of the burner (1) that is configured to generate an ignition spark in the pre-mixing chamber (12) of the burner (1).
 19. The waste gas treatment device (22) according to claim 1, further comprising: a flame holder (13) in the pre-mixing chamber (12) of the burner in order to generate turbulence. 